The Physics Book: From the Big Bang to Quantum Resurrection, 250 Milestones in the History of Physics

A couple of years ago our friend Clifford Pickover wrote the terrifically fun book, The Math Book. Now he's got a new one that's just as good about physics. It's called, as you might guess, The Physics Book and the publisher has kindly given me permission to run some examples from the book. You can check all of them out after the jump.

"Creating a nuclear reaction is not simple," write technologists at the U.S. Department of Energy. "In power plants, it involves splitting uranium atoms, and that process releases energy as heat and neutrons that go on to cause other atoms to split. This splitting process is called nuclear fission. In a power plant, sustaining the process of splitting atoms requires the involvement of many scientists and technicians."

In fact, it was not until the late 1930s that physicists Enrico Fermi and Leo Szilard fully appreciated that uranium would be the element capable of sustaining a chain reaction. Szilard and Fermi conducted experiments at Columbia University and discovered significant Neutron (subatomic particle) production with uranium, proving that the chain reaction was possible and enabling nuclear weapons. Szilard wrote on the night of the discovery, "there was very little doubt in my mind that the world was headed for grief."

Because of the complexity of the process, the world was stunned in 1972 when French physicist Francis Perrin discovered that nature had created the world's first nuclear reactor two billion years before humankind, beneath Oklo in Gabon, Africa. This natural reactor formed when a uranium-rich mineral deposit came in contact with groundwater, which slowed the neutrons (subatomic particles) ejected from the uranium so that they could interact with and split other atoms. Heat was produced, turning the water to steam, thus temporarily slowing the chain reaction. The environment cooled, water returned, and the process repeated.

Scientists estimate that this prehistoric reactor ran for hundreds of thousands of years, producing the various isotopes (atomic variants) expected from such reactions that scientists detected at Oklo. The nuclear reactions in the uranium in underground veins consumed about five tons of radioactive uranium-235. Aside from the Oklo reactors, no other natural nuclear reactors have been identified. Roger Zelazny creatively speculates in his novel Bridges of Ashes that an alien race created the Gabon mine in order to cause mutations that eventually led to the human race.

In 1800, Italian physicist Alessandro Volta invented what has been traditionally considered to be the first electric battery when he stacked several pairs of alternating copper and zinc discs separated by cloth soaked in salt water. When the top and bottom of the pile were connected by a wire, an electric current began to flow. However, the discovery of certain archeological artifacts may suggest batteries predate this discovery by more than a millennium.

"Iraq has a rich national heritage," writes the BBC News. "The Garden of Eden and the Tower of Babel are said to have been sited in this ancient land." In 1938, while in Baghdad, German archeologist Wilhelm Koenig discovered a five-inch-long (13 cm) clay jar containing a copper cylinder that surrounded an iron rod. The jar showed signs of corrosion and seemed to have once contained a mild acid, such as vinegar or wine. Koenig believed these vessels to be galvanic cells, or parts of batteries, possibly used for electroplating gold onto silver objects. The acidic solution would serve as an electrolyte, or conducting medium. The dates of the artifacts are obscure. Koenig dated them to around 250 B.C. to A.D. 224, while others have suggested a range of A.D. 225-640. Subsequent researchers have demonstrated that replicas of the Baghdad Battery do indeed produce electrical current when filled with grape juice or vinegar.

Referring to the batteries in 2003, metallurgist Dr. Paul Craddock notes, "They are a one-off. As far as we know, nobody else has found anything like these. They are odd things; they are one of life's enigmas." Various other uses for the Baghdad batteries have been suggested, ranging from their use to produce electrical currents for the purpose
of acupuncture or to impress worshipers of idols. If wires or conductors are ever discovered along with other ancient batteries, this would support the idea that these objects functioned as batteries. Of course, even if the vessels did produce electric currents, this does not imply that the ancient people understood how the objects actually worked.

In 1814, French mathematician Pierre-Simon Laplace described an entity, later called Laplace's Demon, that was capable of calculating and determining all future events, provided that the demon was given the positions, masses, and velocities of every atom in the universe and the various known formulae of motion. "It follows from Laplace's thinking," writes scientist Mario Markus, "that if we were to include the particles in our brains, free will would become an illusion.... Indeed, Laplace's God simply turns the pages of a book that is already written."

During Laplace's time, the idea made a certain sense. After all, if one could predict the position of billiard balls bouncing around a table, why not entities composed of atoms? In fact, Laplace has no need of God at all in his universe.
Laplace wrote, "We may regard the present state of the universe as the effect of its past and the cause of its future. An intellect which at a certain moment would know all forces that set nature in motion, and all positions of all items of which nature is composed, if this intellect were also vast enough to submit these data to analysis, [it would embrace in] a single formula the movements of the greatest bodies of the universe and those of the tiniest atom; for such an intellect nothing would be uncertain and the future just like the past would be present before its eyes."

Later, developments such as Heisenberg's Uncertainty Principle (HUP) and Chaos Theory appear to make Laplace's demon an impossibility. According to chaos theory, even minuscule inaccuracies in measurement at some initial time may lead to vast differences between a predicted outcome and an actual outcome. This means that Laplace's demon would have to know the position and motion of every particle to infinite precision, thus making the demon more complex than the universe itself. Even if this demon existed outside the universe, the HUP tells us that infinitely precise measurements of the type required are impossible.

"From the time of the earliest civilizations," writes marine physicist Susanne Lehner, "humankind has been fascinated with stories of giant waves--the 'monsters' of the seas... towers of water pounding down on a helpless boat. You can observe the wall of water coming... but you cannot run away and you cannot fight it.... Can we cope with [this nightmare] in the future? Predict extreme waves? Control them? Ride giant waves like surfers?"

It may seem surprising that in the twenty-first century, physicists do not have a complete understanding of the ocean surface, but the origin of rogue waves is not completely clear. In 1826, when French explorer and naval officer Captain Dumont d'Urville reported waves up to 98 feet (30 meters) in height--approximately the height of a 10-story building--he was ridiculed. However, after using satellite monitoring and many models that incorporate the relevant probability theory of wave distributions, we now know that waves this high are much more common than expected. Imagine the horrors of such a wall of water appearing without warning in mid-ocean, sometimes in clear weather, preceded by a trough so deep as to form a frightening "hole" in the ocean.

One theory is that ocean currents and seabed shapes act almost like optical lenses and focus wave actions. Perhaps high waves are generated by the superposition of crossing waves from two different storms. However, additional factors seem to play a role in creating such nonlinear wave effects that can produce the tall wall of water in a relatively calm sea. Before breaking, the rogue wave can have a crest four times higher than crests of neighbor waves. Many papers have been written that attempt to model formation of rogue waves using nonlinear Schroedinger equations. The effect of wind on the nonlinear evolution of waves has also been a productive area of research. Because rogue waves are responsible for the loss of ships and lives, scientists continue to search for ways to predict and avoid such waves.

"Fictional spaceships are often powered by 'antimatter drives'," writes author Joanne Baker, "yet antimatter itself is real and has even been made artificially on the Earth. A 'mirror image' form of matter... , antimatter cannot coexist with matter for long-- both annihilate in a flash of energy if they come into contact. The very existence of antimatter points at deep symmetries in particle physics."

The British physicist Paul Dirac once remarked that the abstract mathematics we study now gives us a glimpse of physics in the future. In fact, his equations from 1928 that dealt with electron motion predicted the existence of antimatter, which was subsequently discovered. According to the formulas, an electron must have an antiparticle with the same mass but a positive electrical charge. In 1932, U.S. physicist Carl Anderson observed this new particle experimentally and named it the positron. In 1955, the antiproton was produced at the Berkeley Bevatron (a particle accelerator). In 1995, physicists created the first anti-hydrogen atom at the CERN research facility in Europe. CERN (Organisation Europeenne pour la Recherche Nucleaire), or the European Organization for Nuclear Research, is the largest particle physics laboratory in the world.

Antimatter-matter reactions have practical applications today in the form of positron emission tomography (PET). This medical imaging technique involves the detection of gamma rays (high-energy radiation) emitted by a positron-emitting tracer radionuclide, an atom with an unstable nucleus.

Modern physicists continue to offer hypotheses to explain why the observable universe appears to be nearly entirely composed of matter and not antimatter. Could regions of the universe exist in which antimatter predominates?

Upon casual inspection, antimatter would be almost indistinguishable from ordinary matter. Physicist Michio Kaku writes, "You can form anti atoms out of anti electrons and antiprotons. Even anti people and anti planets are theoretically possible. [However], antimatter will annihilate into a burst of energy upon contact with ordinary matter. Anyone holding a piece of antimatter in their hands would immediately explode with the force of thousands of hydrogen bombs."

The mind-boggling concept of quantum immortality, and related concepts discussed by technologist Hans Moravec in 1987 and later by physicist Max Tegmark, relies on the many-worlds interpretation (MWI) of quantum mechanics discussed in the entry on Parallel Universes. This theory holds that whenever the universe ("world") is confronted by a choice of paths at the quantum level, it actually follows the various possibilities, splitting into multiple universes.

According to proponents of quantum immortality, the MWI implies that we may be able to live virtually forever. For example, suppose you are in an electric chair. In almost all parallel universes, the electric chair will kill you. However, there is a small set of alternate universes in which you somehow survive--for example an electrical component may fail when the executioner pulls the switch. You are alive in, and thus able to experience, one of the universes in which the electric chair malfunctions. From your own point of view, you live virtually forever.

Consider a thought experiment. Don't try this at home, but imagine that you are in your basement next to a hammer that is triggered or not triggered based on the decay of a radioactive atom. With each run of the experiment, a 50-50 chance exists that the hammer will smash your skull, and you will die. If the MWI is correct, then each time you conduct the experiment, you will be split into one universe in which the hammer smashes and kills you and another universe in which the hammer does not move. Perform the experiment for a thousand times, and you may find yourself to be surprisingly alive. In the universe in which the hammer falls, you are dead. However, from the point of view of the living version of you, the hammer experiment will continue running and you will be alive, because at each branch in the multiverse there exists a version of you that survives. If the MWI is correct, you may slowly begin to notice that you never seem to die!

This medical imaging technique involves the detection of gamma rays (high-energy radiation) emitted by a positron-emitting tracer radionuclide, an atom with an unstable nucleus.

Not quite. It’s true that the tracer decays, and in doing so emits a positron. But the gamma rays themselves are emitted from the electron-positron annihilation event that occurs when the positron encounters an electron; they don’t come directly from the tracer.

The problem with Quantum Immortality is that the outcomes aren’t binary. “You die, or you’re fine”. There are all sorts of gradations in the middle. You fall off a building… sure, in one out of a million universes that stem from that fall, you get up, dust yourself off, and walk away with no problems. In many, many more, you suffer severe injuries that will make the rest of your life unending (because you will never experience the universes in which you die) pain… the same goes for every other scenario – the hammer might shatter your skull and damage your brain, but you survive. The moment you set up the experiment and sit down for it and wait for the decision of the isotope, you’ve got a 50/50 chance of experiencing a universe in which you’re fine, or a universe in which the hammer starts to fall, and whatever happens after that, you live.

I hope QI isn’t true, because if it is, sooner or later, no matter how lucky you are, you’ll wind up in a hell of eternal pain. One in a billion, billion of you might have continued to exist happily alive for centuries, but that’s no more comfort to the rest of you than the thought that one in several million of you just won the lottery yesterday. Once you’ve split off, you don’t get to go back and experience the universes where you had better outcomes. Once you’ve fallen off the building, you will never experience the universe where you just barely missed falling off the building. All that you have left to experience are the universes where the ground’s rushing up, and hope for the one in a million chance that you’re fine, and not the rest of the chances where you’re alive, but wish you weren’t.

It does, if you believe in it, turn out to be a startlingly good argument against attempting suicide, though – why not put off that eternal pain as long as possible?

I agree it’s all deeply troubling (which doesn’t mean it isn’t true!).
If many worlds is true, then ethics and morality go straight out of the window, since it is 100% guaranteed that there will be worlds in which you have gone on mass murder campaigns, no matter how meek you consider yourself. Darwinism is as nothing in terms of cultural shock value compared to many worlds.
That said, it really is an elegant interpretation to put on quantum theory. I recommend reading David Deutsch on this.

Multi-World (better stated as multi-state) interpretation does *not* mean for every possible decision you can make, the universe splits in twain. It means that when a quantum measurement is made, the measurement apparatus is joined in a superposition that is correlated with the superposition of the quantum particle’s states. Your memory of that measurement is part of the measurement apparatus. And since the superposed states cannot communicate with each other, it is merely that you can’t “remember” seeing the measurement be something else.

I like how physics becomes metaphysical and doesn’t have the answers. I also like to hear of clever things that were made in ancient times that we rediscover. The thing that makes me sad is the thought of all the treasures that we have thrown away because we didn’t know what they were for.